In the last several years, we have witnessed the increased use of various auxiliary lift devices, such as wheelchair lifts, lift gates and personal lifts, which are used to allow persons with disabilities or other infirmities to more easily enter and exit vehicles (such as buses, vans and sport utility vehicles (SUV's)). As can be appreciated, when such devices are used, it is important that the vehicle be prevented from moving during the operation of the auxiliary device, insofar as movement of the vehicle can result in injury to the user. Consequently, the Americans with Disabilities Act (ADA), Title 49, Code of Federal Regulations, has implemented various lift interlock requirements to ensure that vehicles will not operate when lift devices are employed.
U.S. Pat. No. 4,420,286, issued to Hanson et al., and U.S. Pat. No. 5,052,879, issued to Wolfe et al., acknowledge that an interlock device used in conjunction with a wheelchair lift, or an invalid lift, must or should be used. For example, Hanson et al. describe an invalid lift apparatus including an interlock switch 186. According to Hanson et al., after the driver brings the vehicle to a stop, the gear shift lever must be placed in the “park” position to close the interlock switch 186, for the invalid lift apparatus to operate.
This patent, however, does not address the use of a parking brake or lift door input as parameters which are also helpful in ensuring that the vehicle will not operate while the lift apparatus is being used. In this respect, the Hanson et al. invention does not lock the vehicle into “park” when the lift door is open, nor when the parking brake is applied, nor does it incorporate system diagnostics and diagnostic displays.
The Wolfe et al. patent is directed to a wheelchair lift and transfer system, and references a “park” cutoff switch 4 (in FIG. 18). The Wolfe et al. system also does not lock the vehicle in “park” when the lift door is open, or when the parking brake is employed, nor does the system incorporate system diagnostics and diagnostic displays.